Investigation of p-type multicolour-broadband quantum dot infrared photodetector

• QDIP based on intervalence subband transition is investigated.
• Theoretical formulation is based on strain dependent k.p theory.
• Analytical expressions for dark current and photocurrent densities are derived.
• Effect of strain on spectral responsivity is discussed.

The feasibility of quantum dot infrared photodetector (QDIP) for the detection of multiple infrared transitions over a broad spectral range is investigated. In contrast to the usual n-type QDIPs, this design utilizes the transitions between the valence subband states for the multicolour broadband functioning. The hole energy levels and corresponding wavefunctions are computed using the strain dependent multiband k.p approach and subsequently used to evaluate the optical matrix elements for intraband transitions. The theoretical formulation is applied to determine the dark current, spectral responsivity and detectivity of the QDIP. The calculated dark current shows good agreement with the experimental data. In addition, we identify the role of strain in determining the responsivity spectra and in shifting the peak response wavelength. We hope that this study would be useful for the further development of QDIPs based on intervalence subband transitions.